As Senegal's veteran leader Abdoulaye Wade and his challenger Macky Sall have made final appeals to voters ahead of Sunday's presidential polls, the election commission called for calm on Saturday.

The commision went on to urge both candidates not to declare premature victory in the runoff which sees the incumbent seeking to extend his rule into his 90s.

African Union observer chief and former Nigerian president Olesegun Obasanjo met both candidates and urged them to "preserve the democratic tradition and heritage in Senegal," one of the continents pioneer democracies.

The head of the EU observer mission, Thijs Berman, called for the "respect of democratic rules" in the west African country whose reputation for stability is on the line.

The elections commission noted several clashes between rival supporters during the election campaign, which was relatively calm compared with that ahead of the first vote on February 26, when riots left six dead.

Victory tour

The 85-year-old Wade had already held a "victory tour" in Dakar on Friday where music rang out as his convoy made its way through the streets on the last day of campaigning ahead of the cliffhanger election in the west African nation.

Wade paused greet thousands of supporters at a rally called the "March Bleue" on the eve of the final round of voting.

The president stood in a moving car and waved at the cheering crowds who followed his convoy.

Having failed to deliver a crushing first-round victory a month ago, Wade faces a challenge from his former prime minister Sall, 50, who has gathered the full weight of the opposition behind him.

Sall held a mass rally in an outlying suburb of Dakar along with 12 candidates who lost in the February 26 first round and have thrown their support behind the challenger as they vow to elect "anyone but Wade”.

While laden with suspense, the run-up to the second round has been calm compared with that of the first round, marred by a month of riots over Wade's candidacy that left six dead and over 150 injured.

The octogenarian's efforts to seek re-election by circumventing a constitutional term limit earned him stiff rebukes from abroad and raised fears for the stability of one of Africa's oldest democracies.

Stone throwing

But our correspondent said there had been a few reports of clashes and stone throwing between opposition youth supporters and Wade supporters, although no reports of injuries.

Wade polled 34.8 per cent in the first round and said he failed to win outright because "the West was campaigning against me”.

Sall placed second in the first round, gaining 26.5 per cent of ballots. But the odds appear to be in Sall's favour heading into Sunday's runoff, with many of the other first round candidates, who collectively won 65 per cent of the vote, spreading out across the country to campaign for him.

Youssou Ndour, the influential music star-turned-politician who was barred from standing in the first round, has also backed Sall.

"Let nobody question our victory. Anyone who tries to steal our victory will face the full mobilisation of the population," Sall said at a rally this week.

While Sall won the backing of the opposition, Wade scored the official support of a leading member of the country's most powerful Islamic brotherhood, the Mourides, seen as key in the Muslim majority nation.

The head of the 90-person European Union observer mission, Thijs Berman, called Friday for "a respect of democratic rules", adding that "violence achieves nothing".

Wade defiant

Meanwhile, African Union observer chief, former Nigerian president Olesegun Obasanjo, said: "Senegal is a grand democracy. I hope it will prove this once again in this run-off election and become a model for other African countries."

Wade has remained defiant in the face of criticism. "There is only one hypothesis. I win. The possibility of my defeat is absurd," he told local television station Africa7 on Wednesday.

"It is as if I say the sky is going to fall on our heads in one minute. It is absurd because the sky is not going to fall on our heads."

A Wade victory would stoke fears of violence after his mere presence in the race prompted opposition supporters to take to the streets.Despite having served two terms in office, a limit he himself introduced, Wade says later changes to the constitution allow him to serve two more successive mandates.

Officially the second oldest African leader after Zimbabwe's 88-year-old Robert Mugabe, some claim Wade is in fact pushing 90 due to discrepancies in the way birth certificates were filed at the time he was born in a nation where the median age is now 18.

In 2007, he won elections in the first round with 55 per cent, but his popularity has plunged in recent years amid rising food prices and power cuts which crippled economic activity last year but were repaired in time for the election campaign.